Topology Optimization Of Hinge-free Compliant Mechanisms Using A Level Set Method

Compliant mechanisms have been paid more attention and become one of the internationalresearch hotspots due to their inherent advantages and potential of being used in the micro-nano-manipulation or precision measurement area. To broaden compliant mechanisms’ applications,consolidating their theoretical basis and design methods is the key. That is the background ofthis dissertation in which the focus is on designing distributed compliant mechanisms usinglevel set methods.Firstly, several methods are developed to overcome the inherent shortcomings of the con-ventional level set method, include:(I) presenting a new distance-remaining functional for-mulation that forces the level set function to be close to a signed distance function during theoptimization process, and therefore completely eliminates the need of the costly re-initializationprocedure;(II) presenting a topology-adjusting scheme which allows new holes being automat-ically generated in the design domain and obtains optimized configurations even being startedfrom a minimum possible initial guess;(III) presenting a predictor-corrector scheme for con-structing velocity field and a shape sensitivity filtering scheme which both can converge withless iterations and thus improve the overall computational efciency.Secondly, the underlying reason of de facto hinges of using spring model to design com-pliant mechanisms is analyzed. A performance diference minimization method for the topol-ogy optimization of compliant mechanisms aimed at eliminating de facto hinges is developed.Based on the method, several alternative formulation are developed. The validity and versatilityof the method are examined using several topology optimization approaches, such as the levelset methods and SIMP method.Thirdly, for designing compliant mechanisms without using the output spring, a method isdeveloped by inserting the input and output mean compliance into the optimization model. Anew objective function is developed using the weighting sum method. The weighting factorsare set based on the information that is obtained from the previous iteration and automaticallyupdated with each optimization iteration step. The validity and versatility of the method are ex-amined using several topology optimization approaches to design compliant mechanisms withboth single input-output behaviour and multiple outputs behaviour.Finally, conclusions and future works are put forward This work will surely provide the theoretical support both in developing more powerfuland efcient level set-based topology optimization method and in consolidating the theoreticalbasis of designing compliant mechanisms.